Programming and Problem Solving with Java

(^112) | Arithmetic Expressions

Increment and Decrement Operators

In addition to the familiar arithmetic operators, Java providesincrementanddecrement operators:

++ Increment

-- Decrement

These unary operators take a single variable name as an operand. For integer and floating-

point operands, the effect is to add 1 to (or subtract 1 from) the operand. If numcurrently con-

tains the value 8, for example, the statement

num++;

causes numto contain 9. You can achieve the same effect by writing the assignment statement

num = num + 1;

Java programmers, however, typically prefer the increment operator.

The ++and --operators can be either prefix operators

++num;

or postfix operators

num++;

Both of these statements behave in exactly the same way; that is, they add 1 to whatever is

in num. The choice between the two is a matter of personal preference, although most Java pro-

grammers favor the latter form.

Java allows you to use ++and --in the middle of a larger expression:

alpha = num++ * 3;

In this case, the postfix form of ++gives a different result from the prefix form. In Chapter

10, we examine the ++and --operators in more detail. In the meantime, you should use

them only to increment or decrement a variable as a separate, stand-alone statement:

Variable ++ ;

++ Variable ;

Increment-Statement

Variable –– ;

–– Variable ;

Decrement-Statement